Porous silicon microcavities for biosensing applications

Porous silicon microcavity resonators possess the unique characteristics of line narrowing and luminescence enhancement. The emission peak position is completely tunable by changing the properties of the central layer. increa sing the thickness of the central active layer introduces multiple narrow p eaks in the luminescence spectrum. Narrow and visible luminescence peaks ar e observed with a full width at hall the maximum (FWHM) value of 3 nm. The microcavity structure is highly sensitive and any slight change in the effe ctive optical thickness modifies the reflectivity spectra, causing a spectr al shift in the interference peaks. This makes porous silicon microcavities an ideal host for sensor applications. We demonstrate the usefulness of th is microcavity resonator structure as a biosensor. A DNA biusensor]las been fabricated based on a porous silicon multiple peak microcavity structure. Shifts in the luminescence spectra are observed and detected for various DN A concentrations. When exposed to a non-complementary DNA strand, no shifts are observed. An extension of the DNA biosensor has been made to include t he detection of viral DNA. Both sensor fabrication and results of extensive testing are presented in this report.